Herbicide Effects on Bacterial Communities and Soil Functions in Rice Agroecosystems: A Critical Narrative Review

Rice fields are complex agroecosystems in which soil bacterial communities play essential roles in nutrient cycling, organic matter decomposition, soil fertility, and plant health. Herbicides are widely used in rice production to control weeds and enhance crop productivity; however, their effects extend beyond target plants and influence non-target soil microorganisms. This narrative review synthesises current knowledge on how herbicides influence bacterial populations in rice ecosystems. Evidence indicates that herbicide application often causes short-term reductions in bacterial abundance, microbial biomass, and soil enzymatic activities, particularly during the first few weeks after application. Nevertheless, many bacterial communities exhibit partial or complete recovery as herbicide residues degrade over time. Herbicides can alter bacterial community composition by suppressing sensitive functional groups, including nitrifying and nitrogen-fixing bacteria, while promoting herbicide-degrading taxa such as certain Bacillus and Actinobacteria species. These shifts may affect critical ecosystem processes, especially nitrogen cycling, nutrient availability, and soil multifunctionality. Long-term or excessive herbicide exposure can reduce microbial diversity, simplify ecological networks, and weaken soil resilience, potentially compromising sustainable rice production. The review also highlights how rice establishment systems, herbicide dosage, and environmental conditions influence bacterial responses. Emerging alternatives, including bioorganic fertilizers, microbial inoculants, integrated weed management, and microbiome-based remediation approaches, show promise for minimizing adverse effects on soil bacteria while maintaining effective weed control.